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[instcombine] Fix oss-fuzz 39934 (mul matcher can match non-instruction) 

Fixes a crash observed by oss-fuzz in 39934.  Issue at hand is that code expects a pattern match on m_Mul to imply the operand is a mul instruction, however mul constexprs are also valid here.
This commit is contained in:
Philip Reames 2021-10-23 18:07:21 -07:00
parent 850217686e
commit 3c06ecaa1e
2 changed files with 10 additions and 2 deletions
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4
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -4184,8 +4184,8 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
if (match(Op0, m_Mul(m_Value(X), m_APInt(C))) && *C != 0 &&
match(Op1, m_Mul(m_Value(Y), m_SpecificInt(*C))) && I.isEquality())
if (!C->countTrailingZeros() ||
(BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap()) ||
(BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap()))
(BO0 && BO1 && BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap()) ||
(BO0 && BO1 && BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap()))
return new ICmpInst(Pred, X, Y);
}

8
llvm/test/Transforms/InstCombine/icmp-mul.ll
View File

@ -668,3 +668,11 @@ define <2 x i1> @eq_mul_constants_with_tz_splat(<2 x i32> %x, <2 x i32> %y) {
%C = icmp eq <2 x i32> %A, %B
ret <2 x i1> %C
}
@g = extern_weak global i32
define i1 @oss_fuzz_39934(i32 %arg) {
%B13 = mul nsw i32 %arg, -65536
%C10 = icmp ne i32 mul (i32 or (i32 zext (i1 icmp eq (i32* @g, i32* null) to i32), i32 65537), i32 -65536), %B13
ret i1 %C10
}